A word to the wise: should you go to see Adam Riches' new show, don't sit in the front row. Don't sit in the second, either. The comedian has been known to whip out the front set of seats at the last minute and leave the complacent audience members behind exposed, "just for a little bit of an extra frisson".
The truth is, there isn't a safe seat in the house when it comes to an Adam Riches show. He doesn't go in for merciless teasing or savaging hecklers like your traditional stand-up. More likely, he'll drag you up on stage for a quick game of Swingball before sending you back to your seat with an aggressive smooch. In August, he won the Edinburgh Comedy Award for a uniquely silly show which crossed surreal character sketches with health-and-safety baiting, It's a Knockout-style games. Unsuspecting members of the afternoon audience were hauled out of the stalls to race skateboards across the stage, take part in an acting masterclass with "Daniel Day-Lewis" or play a tense round of blind Mastermind.
Refusing is not an option: I should know. The first time I went to see one of Riches' shows, a few years ago, I was dragged up – kicking, muttering and waving my critic's notebook, all to no avail – to rank the chest hair of three male audience members for an excruciating game. Since then, his shows have become ever more fearlessly participatory, culminating in last summer's 60 minutes of controlled chaos. Infectious and properly irresistible, it is now coming to the Soho Theatre in London for a five-week victory run.
"When you're constructing an hour, you think about how you want it to be," says Riches, far more softly spoken than his anarchic on-stage persona. "Do you want the audience to take a breather at this point, bring the fourth wall back in and do some character stuff? Or do you want to just go at them even more? This year the decision was – don't stop. There was no chance I would ever be stopped. You were on stage whether you liked it or not."
If it sounds terrifying, it is, but it's also extremely funny. The key to Riches' charm is that he never humiliates his stooges more than he humiliates himself. His characters are ludicrous paragons of machismo – a bellowing leading man, a big-game hunter laid low by his own oversized dinghy, a sleazy bartender or a Latino Swingball champion who wears a headband "woven from all the hamstrings he's ever torn". In the end, it's always the audience members who are the heroes.
And if it looks like a shambles, don't be fooled, it's precision-controlled. From the minute his audience files in, Riches is watching, doing a "stocktake", to assess who might make a good victim. "You can spot the eager ones and you really don't want that," he says. "It may be funny for a moment but it will ruin the dynamic of me teasing something out of someone until they deliver." During the show, he is constantly adapting his script, choosing "different jukebox tracks" depending on the mood. Has he ever made anyone cry? "Not onstage. I've definitely seen shaken people. It's really important to have confidence in it. What's the worst that can happen? If it bombs, it bombs."
His fearlessness stems partly from the fact that pretty much the worst thing that can happen has already happened. In 2008, Riches was midway through Alpha Males in Edinburgh when he broke his leg in four places, live on stage. More precisely, his 6ft 7in younger brother, James, also an actor, broke it during a choreographed fight.
"Because James had come out of the audience everyone just figured it was a laugh, another stooge bit," recalls Riches. "I said to the technician, 'No, seriously, I've broken my leg. Can you put the lights up? And can someone call an ambulance?' That got a big laugh." Eventually, he was stretchered off but was back on stage only five days later, performing two shows a day from his wheelchair.
The accident put fire in his belly to make a success of a career that had yet to take off. Now, at the age of 38, his dogged determination is starting to pay off. "Fourteen years into a 15-year career, I'm beginning to earn money," smiles Riches, who lives in Kew with his actress girlfriend. "And my mum has an award on her mantelpiece."
He was born in Cambridge, one of four boys, and was brought up in Glasgow and then London. Moving schools, he lost focus on his studies and left before finishing his A-levels to work at Eurodisney. He wanted to play a character but, too tall for Tigger and too short for Baloo the bear, he ended up working as a waiter, until he was fired for being cheeky. Back home, he applied for a media and performance course at Salford University, faking his grades, forging his application form and performing his way through the interview. It worked – and he spent three happy years writing dark little homages to Beckett and Pinter that he starred in and directed himself.
After graduating, he spent years playing bit parts on television until one day, on the set of a hospital soap, he couldn't get his lines out. He went back to his agents and told them that he wanted to try character comedy, inspired by his childhood hero, Jack Lemmon.
His first show at the Edinburgh Fringe in 2003, a Hamm and Clov-style tale of two fading lounge musicians got a lukewarm response. Undeterred, he pressed on with a further four solo efforts, slowly building a following. Last year, with participation the buzzword of the Fringe, he captured the zeitgeist. Was he surprised to win the award? "Yes. I was just doing the same stuff, with the same mentality, and the same enthusiasm. It feels strange to have an award attached to that."
Like other recent idiosyncratic winners Tim Key, Daniel Kitson and Laura Solon, Riches is unlikely to go the route of stadiums and panel shows. Instead, he's working on a "rambunctious" live audience-interaction show for television. He'd love to develop a British equivalent of Saturday Night Live, which would be the ideal vehicle for his Will Ferrell-style absurd characters and anarchic energy.
Translating the strange maniacal magic of his stage shows to a wider audience will be a tricky task, but after 15 years, Riches is happy to take his time to get it right. "On the Fringe, year upon year, acts that are left uninterfered with, to get it wrong are thriving", he says. "I buggered up royally in Edinburgh – physically and creatively – and from that I crafted something. The lesson I always go to in darker moments is 'just wait'. I have waited and now this has happened."
'Bring Me the Head of Adam Riches', Soho Theatre, London W1 (020 7478 0100; www.sohotheatre.com ) to 17 March